Image decoding method, image coding method, image decoding apparatus, and image coding apparatus

ABSTRACT

An image decoding method for decoding an image including slices while reducing both a decrease in image quality and a decrease in coding efficiency is provided. The image decoding method includes: decoding a current motion vector which is a motion vector of a current block to be decoded and specifies a reference block included in a reference picture, and a difference image block indicating a difference between the current block and a prediction image block; generating the prediction image block by allocating, to an outside pixel that is a pixel included in the reference block and located outside an associated slice that is a slice corresponding to a current slice to be decoded which includes the current block, a value of an inside pixel that is a pixel located inside the associated slice; and adding up the difference image block and the prediction image block to reconstruct the current block.

TECHNICAL FIELD

The present invention relates to an image decoding method for decoding,on a per-block basis, pictures each including slices.

BACKGROUND ART

In an image coding process, a quantity of information is generallyreduced by lessening redundancy in spatial and temporal directions. Tolessen the redundancy in the spatial direction, an intra-frame (intra)prediction coding process is applied. To lessen the redundancy in thetemporal direction, an inter-frame (inter) prediction coding process isapplied.

In the inter-frame prediction coding process, a coded picture locatedbefore or after, in display order, a current picture to be coded is usedas a reference picture. Through motion estimation between the referencepicture and the current picture, a motion vector is then derived. Next,motion compensation using the motion vector is performed to generateprediction image data. Subsequently, the prediction image data issubtracted from image data of the current picture, with the result thatthe redundancy in the temporal direction is removed.

In the motion estimation, values of difference between a current blockto be coded in the current picture and blocks in the reference pictureare calculated, and one of the blocks in the reference picture for whichthe difference value is smallest is determined as a reference block.Using the current block and the reference block, a motion vector is thenestimated.

In the moving picture coding scheme called H. 264, which has alreadybeen standardized, three types of pictures: I-picture, P-picture, andB-picture, are used to reduce the quantity of information. For theI-picture, no inter-frame prediction coding process is performed. Inother words, for the I-picture, only an intra-frame prediction codingprocess is performed.

For coding the P-picture and the B-picture, inter-frame predictioncoding is applied. For coding the P-picture, one coded reference picturelocated before or after the current picture in display order is referredto. For coding the B-picture, two coded reference pictures locatedbefore or after the current picture in display order are referred to.From reference blocks included in these reference pictures, predictionimage data is obtained.

The motion vector usually points to a reference block in a referencepicture. When the reference block pointed to by the motion vector isoutside the reference picture, no pixel value can be obtained unlesstreated. There is therefore a restriction that the motion vector pointsto a reference block within the reference picture. Alternatively, apixel value is copied from inside to outside of the reference picture.By doing so, prediction image data is obtained from a reference blockoutside the reference picture. Copying a pixel value from inside tooutside of a reference picture is also referred to as pixel stretching.

FIG. 35A is a conceptual diagram showing a prediction image generationprocess according to the related art. In FIG. 35A, a motion vector of acurrent block to be processed, included in a current picture to beprocessed, points to a reference block located on a boundary of thereference picture. In such a case, there is no pixel value at, in thereference block, a pixel position outside the range of the referencepicture unless a stretching process is performed, resulting in a failureto obtain effective prediction image data.

FIG. 35B is a conceptual diagram showing pixel stretching according tothe related art. In the reference block, a value of a pixel locatedinside the reference picture is copied to a pixel located outside thereference picture. By doing so, the pixel located outside iscomplemented with the value. Thus, effective prediction image data isobtained.

Patent Literature (PTL) 1 discloses a pixel stretching method.

[Citation List] [Patent Literature] [PTL 1] Japanese Unexamined PatentApplication Publication No. 2001-61150 SUMMARY OF INVENTION [TechnicalProblem]

However, even in the case where the motion vector points to a positionwithin the reference picture, there is a possibility that the motionvector points to a position which is not appropriate for predictionimage generation. For example, in H. 264, a picture may be divided intoa plurality of slices. In this case, the information for use inintra-frame prediction is limited to information obtained from an imagewithin the slice. Such limitation makes it possible to perform aparallel coding process or a parallel decoding process.

Furthermore, the slices which are different from each other may havedifferent image characteristics. In such a case, limiting theinformation for use in intra-frame prediction to the information withinthe slice allows improvements in image quality, processing efficiency,and compression rate (also referred to as coding efficiency).

On the other hand, in inter-frame prediction, even when a picture isdivided into slices, information on another slice included in anotherpicture is usually referred to. Furthermore, since a boundary of a sliceis not treated as an end of a picture, the slice is not enlarged. Thus,the use of information on another slice at the time of coding degradesimage quality especially in a slice boundary area. In response, also ininter-frame prediction, it is conceivable to limit the use of anotherslice.

However, when referring to another slice is limited, the motion vectoris forcibly changed in the slice boundary area so as to point to aposition within the slice. In such a case, the motion vector is largelydifferent between the slice boundary area and the other areas. Thislowers the coding efficiency of the motion vector.

Specifically, a motion vector difference, which is a value of differencebetween motion vectors indicating substantially the same movement, iscoded as a motion vector, thereby improving the coding efficiency.However, in the case where the motion vector largely changes, thedifference becomes large accordingly, which lowers the codingefficiency.

Thus, the present invention aims to provide an image decoding method fordecoding an image including a plurality of slices while reducing both adecrease in image quality and a decrease in coding efficiency.

[Solution to Problem]

In order to solve the above problem, the image decoding method accordingto an aspect of the present invention is an image decoding method fordecoding, on a per-block basis, pictures each including slices, themethod comprising: decoding a current motion vector and a differenceimage block, the current motion vector being a motion vector of acurrent block to be decoded and specifying a reference block included ina reference picture, and the difference image block indicating adifference between the current block and a prediction image block;generating the prediction image block by allocating a value of an insidepixel to an outside pixel, the inside pixel being a pixel located insidean associated slice, the outside pixel being a pixel located outside theassociated slice and included in the reference block specified by thecurrent motion vector, and the associated slice being a slice includedin the reference picture and corresponding to a current slice to bedecoded which includes the current block; and adding up the differenceimage block and the prediction image block to reconstruct the currentblock.

Furthermore, it may be that the image decoding method comprises storing,into a memory unit, identification information for identifying a rangeof the associated slice specified in each of reference pictures, and inthe generating, the outside pixel and the inside pixel are determined byreferring to the identification information stored in the memory unit,and the value of the inside pixel is allocated to the outside pixel togenerate the prediction image block.

Furthermore, it may be that in the decoding, the identificationinformation is decoded, and in the storing, the identificationinformation resulting from the decoding is stored into the memory unit.

Furthermore, it may be that in the storing, the identificationinformation is stored into the memory unit when the range of theassociated slice has been changed.

Furthermore, it may be that in the decoding, applicability informationis decoded, the applicability information indicating whether or not thevalue of the inside pixel is to be allocated to the outside pixel of thereference block, and in the generating, when the applicabilityinformation indicates that the value of the inside pixel is to beallocated to the outside pixel, the value of the inside pixel isallocated to the outside pixel of the reference block to generate theprediction image block.

Furthermore, it may be that the decoding includes decoding theapplicability information indicating whether or not the value of theinside pixel is to be allocated to the outside pixel of the referenceblock which includes a boundary of the associated slice, and in thegenerating, when the applicability information indicates that the valueof the inside pixel is to be allocated, the value of the inside pixel isallocated to the outside pixel of the reference block which includes theboundary of the associated slice, to generate the prediction imageblock.

Furthermore, it may be that the decoding includes decoding theapplicability information indicating whether or not the value of theinside pixel is to be allocated to the outside pixel of the referenceblock which is entirely included in a non-associated slice differentfrom the associated slice, and in the generating, when the applicabilityinformation indicates that the value of the inside pixel is to beallocated, the value of the inside pixel is allocated to the outsidepixel of the reference block which is entirely included in thenon-associated slice, to generate the prediction image block.

Furthermore, it may be that in the decoding, an offset value forshifting the associated slice is decoded, and in the generating, theassociated slice is shifted by as much as the offset value, and thevalue of the inside pixel which is a pixel located inside the associatedslice resulting from the shifting is allocated to the outside pixelwhich is a pixel located outside the associated slice resulting from theshifting, to generate the prediction image block.

Furthermore, it may be that in the generating, the value of the insidepixel which is a pixel spatially closest to the outside pixel amongpixels included in the associated slice is allocated to the outsidepixel, to generate the prediction image block.

Furthermore, an image coding method according to an aspect of thepresent invention is an image coding method for coding, on a per-blockbasis, pictures each including slices, the method comprising: estimatinga current motion vector which is a motion vector of a current block tobe coded and specifies a reference block included in a referencepicture; generating a prediction image block by allocating a value of aninside pixel to an outside pixel, the inside pixel being a pixel locatedinside an associated slice, the outside pixel being a pixel locatedoutside the associated slice and included in the reference blockspecified by the current motion vector, and the associated slice being aslice included in the reference picture and corresponding to a currentslice to be coded which includes the current block; subtracting theprediction image block from the current block to generate a differenceimage block; and coding the current motion vector and the differenceimage block.

Furthermore, it may be that the image coding method comprises storing,into a memory unit, identification information for identifying a rangeof the associated slice specified in each of reference pictures, and inthe generating, the outside pixel and the inside pixel are determined byreferring to the identification information stored in the memory unit,and the value of the inside pixel is allocated to the outside pixel togenerate the prediction image block.

Furthermore, it may be that in the coding, the identificationinformation is coded.

Furthermore, it may be that in the storing, the identificationinformation is stored into the memory unit when the range of theassociated slice has been changed.

Furthermore, it may be that in the coding, applicability information iscoded, the applicability information indicating whether or not the valueof the inside pixel is to be allocated to the outside pixel of thereference block, and in the generating, when the applicabilityinformation indicates that the value of the inside pixel is to beallocated to the outside pixel, the value of the inside pixel isallocated to the outside pixel of the reference block to generate theprediction image block.

Furthermore, it may be that the coding includes coding the applicabilityinformation indicating whether or not the value of the inside pixel isto be allocated to the outside pixel of the reference block whichincludes a boundary of the associated slice, and in the generating, whenthe applicability information indicates that the value of the insidepixel is to be allocated, the value of the inside pixel is allocated tothe outside pixel of the reference block which includes the boundary ofthe associated slice, to generate the prediction image block.

Furthermore, it may be that the coding includes coding the applicabilityinformation indicating whether or not the value of the inside pixel isto be allocated to the outside pixel of the reference block which isentirely included in a non-associated slice different from theassociated slice, and in the generating, when the applicabilityinformation indicates that the value of the inside pixel is to beallocated, the value of the inside pixel is allocated to the outsidepixel of the reference block which is entirely included in thenon-associated slice, to generate the prediction image block.

Furthermore, it may be that in the coding, an offset value for shiftingthe associated slice is coded, and in the generating, the associatedslice is shifted by as much as the offset value, and the value of theinside pixel which is a pixel located inside the associated sliceresulting from the shifting is allocated to the outside pixel which is apixel located outside the associated slice resulting from the shifting,to generate the prediction image block.

Furthermore, it may be that in the generating, the value of the insidepixel which is a pixel spatially closest to the outside pixel amongpixels included in the associated slice is allocated to the outsidepixel, to generate the prediction image block.

Furthermore, an image decoding apparatus according to an aspect of thepresent invention may be an image decoding apparatus for decoding, on aper-block basis, pictures each including slices, the apparatuscomprising: a decoding unit configured to decode a current motion vectorand a difference image block, the current motion vector being a motionvector of a current block to be decoded and specifying a reference blockincluded in a reference picture, and the difference image blockindicating a difference between the current block and a prediction imageblock; a prediction image generation unit configured to generate theprediction image block by allocating a value of an inside pixel to anoutside pixel, the inside pixel being a pixel located inside anassociated slice, the outside pixel being a pixel located outside theassociated slice and included in the reference block specified by thecurrent motion vector, and the associated slice being a slice includedin the reference picture and corresponding to a current slice to bedecoded which includes the current block; and an addition unitconfigured to add up the difference image block and the prediction imageblock to reconstruct the current block.

Furthermore, an image coding apparatus according to an aspect of thepresent invention may be an image coding apparatus for coding, on aper-block basis, pictures each including slices, the apparatuscomprising: a motion estimation unit configured to estimate a currentmotion vector which is a motion vector of a current block to be codedand specifies a reference block included in a reference picture; aprediction image generation unit configured to generate a predictionimage block by allocating a value of an inside pixel to an outsidepixel, the inside pixel being a pixel located inside an associatedslice, the outside pixel being a pixel located outside the associatedslice and included in the reference block specified by the currentmotion vector, and the associated slice being a slice included in thereference picture and corresponding to a current slice to be coded whichincludes the current block; a subtraction unit configured to subtractthe prediction image block from the current block to generate adifference image block; and a coding unit configured to code the currentmotion vector and the difference image block.

[Advantageous Effects of Invention]

Using the present invention, a prediction image is appropriatelygenerated even in the case where an image is divided into a plurality ofslices. Thus, the decrease in image quality and the decrease in codingefficiency are reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structure diagram showing an image decoding apparatusaccording to Embodiment 1.

FIG. 2 is a flowchart showing an image decoding process according toEmbodiment 1.

FIG. 3A is a conceptual diagram showing the first example of predictionimage generation according to Embodiment 1.

FIG. 3B is a conceptual diagram showing a stretching process accordingto Embodiment 1.

FIG. 4A is a conceptual diagram showing the second example of predictionimage generation according to Embodiment 1.

FIG. 4B is a conceptual diagram showing the second example of thestretching process according to Embodiment 1.

FIG. 5 is a flowchart showing a prediction image generation processaccording to Embodiment 1.

FIG. 6 is a flowchart showing a variation of the prediction imagegeneration process according to Embodiment 1.

FIG. 7A is a conceptual diagram showing the first example of a slicestructure according to Embodiment 1.

FIG. 7B is a conceptual diagram showing the second example of the slicestructure according to Embodiment 1.

FIG. 7C is a conceptual diagram showing the third example of the slicestructure according to Embodiment 1.

FIG. 8A is a conceptual diagram showing the third example of predictionimage generation according to Embodiment 1.

FIG. 8B is a conceptual diagram showing the third example of thestretching process according to Embodiment 1.

FIG. 9A is a conceptual diagram showing the fourth example of predictionimage generation according to Embodiment 1.

FIG. 9B is a conceptual diagram showing an example of identificationinformation according to Embodiment 1.

FIG. 10 is a structure diagram showing a specific example of the imagedecoding apparatus according to Embodiment 1.

FIG. 11 is a flowchart showing a specific example of the image decodingprocess according to Embodiment 1.

FIG. 12 is a structure diagram showing an image coding apparatusaccording to Embodiment 1.

FIG. 13 is a flowchart showing an image coding process according toEmbodiment 1.

FIG. 14 is a structure diagram showing a specific example of an imagecoding apparatus according to Embodiment 1.

FIG. 15 is a flowchart showing a specific example of the image codingprocess according to Embodiment 1.

FIG. 16 illustrates an overall configuration of a content providingsystem for implementing content distribution services.

FIG. 17 illustrates an overall configuration of a digital broadcastingsystem.

FIG. 18 is a block diagram illustrating an example of a configuration ofa television.

FIG. 19 is a block diagram illustrating an example of a configuration ofan information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk.

FIG. 20 shows an example of a configuration of a recording medium thatis an optical disk.

FIG. 21A shows an example of a cellular phone.

FIG. 21B shows an example of a configuration of the cellular phone.

FIG. 22 illustrates a structure of the multiplexed data.

FIG. 23 schematically illustrates how each of streams is multiplexed inmultiplexed data.

FIG. 24 illustrates how a video stream is stored in a stream of PESpackets in more detail.

FIG. 25 shows a structure of TS packets and source packets in themultiplexed data.

FIG. 26 shows a data structure of a PMT.

FIG. 27 shows an internal structure of multiplexed data information.

FIG. 28 shows an internal structure of stream attribute information.

FIG. 29 shows steps for identifying video data.

FIG. 30 is a block diagram illustrating an example of a configuration ofan integrated circuit for implementing the moving picture coding methodand the moving picture decoding method according to each embodiment.

FIG. 31 shows a configuration for switching between driving frequencies.

FIG. 32 shows steps for identifying video data and switching betweendriving frequencies.

FIG. 33 shows an example of a look-up table in which standards of videodata are associated with the driving frequencies.

FIG. 34A shows an example of a configuration for sharing a module of asignal processing unit.

FIG. 34A shows another example of a configuration for sharing a moduleof a signal processing unit.

FIG. 35A is a conceptual diagram showing prediction image generationaccording to the related art.

FIG. 35B is a conceptual diagram showing a stretching process accordingto the related art.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are described below with referenceto the drawings. It is to be noted that each of Embodiments describedbelow illustrates one desirable specific example of the presentinvention. Numerical values, shapes, materials, structural elements, thearrangement and connection of the structural elements, steps, an orderof the steps, and the like in the following Embodiments are an exampleof the present invention, and it should therefore not be construed thatthe present invention is limited to each of these Embodiments.Furthermore, out of the constituents in the following Embodiments, theconstituents not stated in the independent claims describing thebroadest concept of the present invention are described as givenconstituents in a more desirable embodiment.

Embodiment 1

FIG. 1 is a structure diagram showing an image decoding apparatusaccording to this embodiment. An image decoding apparatus 100 shown inFIG. 1 decodes, on a per-block basis, pictures each including slices.Furthermore, the image decoding apparatus 100 includes a decoding unit101, a prediction image generation unit 102, and an addition unit 103. Ablock herein is typically a macroblock, but may be a block which ismeasured in units different from the macroblock.

The decoding unit 101 decodes a motion vector (also referred to as acurrent motion vector) and a difference image block. The motion vectorhere is a motion vector of a current block to be decoded and is used tospecify a reference block included in a reference picture. Thedifference image block here is a block generated in a coding process andmade up of pixel values which indicate differences between pixel valuesof the current block and pixel values of a prediction image block.Typically, the decoding unit 101 performs variable-length decoding onthe motion vector and the difference image block.

The prediction image generation unit 102 specifies a reference block ina reference picture using the motion vector and generates a predictionimage block. At this time, the prediction image generation unit 102performs pixel stretching at a slice boundary. Specifically, theprediction image generation unit 102 allocates a value of an insidepixel that is a pixel located inside an associated slice to an outsidepixel that is a pixel located outside the associated slice and includedin the reference block.

Here, the associated slice is a slice included in the reference pictureand has identity with a current slice to be decoded which includes thecurrent block. The current slice and the associated slice have videocontent (content) in common. Typically, the spatial position of theassociated slice in the reference picture matches the spatial positionof the current slice in the current picture. Alternatively, the area ofthe associated slice and the area of the current slice spatiallyoverlap.

In other words, the associated slice is a slice which is included in thereference picture and corresponds to the current slice including thecurrent block.

It is to be noted that the inside pixel may be located either inside oroutside the reference block. As the value of the inside pixel, theprediction image generation unit 102 preferably allocates, to theoutside pixel, a value of a pixel which is spatially closest to theoutside pixel among the pixels included in the associated slice. Twopixels which are spatially close are likely to be similar to each other.Thus, the prediction image generation unit 102 is capable of improvingprediction accuracy by allocating a spatially close pixel value.

The addition unit 103 adds up the difference image block decoded by thedecoding unit 101 and the prediction image block generated by theprediction image generation unit 102. Specifically, the addition unit103 adds up the pixel values included in the difference image block andthe pixel values included in the prediction image block, therebycombining the difference image block and the prediction image block. Bydoing so, the addition unit 103 reconstructs the current block.

FIG. 2 is a flowchart showing an image decoding process according to theimage decoding apparatus 100 shown in FIG. 1.

First, the decoding unit 101 decodes the motion vector and thedifference image block (S101). Next, the prediction image generationunit 102 allocates the value of the inside pixel to the outside pixeland generates the prediction image block (S102). Lastly, the additionunit 103 adds up the difference image block and the prediction imageblock (S103). By doing so, the current block is reconstructed.

FIG. 3A is a conceptual diagram showing the first example of predictionimage generation according to this embodiment. In FIG. 3A, the currentblock is included in a second slice of the current picture. A motionvector of the current block points to the reference block located on theboundary between a first slice and the second slice in the referencepicture. In this case, the prediction image generation unit 102stretches a pixel in the second slice into the first slice.

FIG. 3B is a conceptual diagram showing an example of a stretchingprocess according to the prediction image generation shown in FIG. 3A.In FIG. 3B, a plurality of outside pixels and a plurality of insidepixels are shown. The outside pixels are included both in the firstslice and in the reference block. The inside pixels are included both inthe second slice and in the reference block. The prediction imagegeneration unit 102 allocates, to each of the outside pixels, the valueof one of the inside pixels which is closest to the outside pixel. Bydoing so, the prediction image generation unit 102 stretches a pixel inthe second slice into the first slice.

FIG. 4A is a conceptual diagram showing the second example of predictionimage generation according to this embodiment. In FIG. 4A, the currentblock is included in a second slice of the current picture as in thecase of FIG. 3A. A motion vector of the current block points to thereference block. In FIG. 4A, a first slice of the reference pictureincludes the whole reference block. Also in this case, the predictionimage generation unit 102 stretches a pixel in the second slice into thefirst slice.

FIG. 4B is a conceptual diagram showing an example of a stretchingprocess according to the prediction image generation shown in FIG. 4A.In FIG. 4B, a plurality of outside pixels and a plurality of insidepixels are shown. The outside pixels are included both in the firstslice and in the reference block. In other words, all the pixelsincluded in the reference block are outside pixels in FIG. 4B. Theinside pixels are included in the second slice. In FIG. 4B, these insidepixels are not included in the reference block.

The prediction image generation unit 102 allocates, to each of theoutside pixels, the value of one of the inside pixels which is closestto the outside pixel. By doing so, the prediction image generation unit102 stretches a pixel in the second slice into the first slice.

FIG. 5 is a flowchart showing a prediction image generation processaccording to the image decoding apparatus 100 shown in FIG. 1 and showsdetails of the prediction image generation process (S102) shown in FIG.2.

First, the prediction image generation unit 102 checks a positionalrelationship between the reference block specified by the motion vectorand the associated slice included in the reference picture. Theassociated slice is a slice which has identity with the current slice asdescribed above.

When the reference block includes a boundary of the associated block(Yes in S201), the prediction image generation unit 102 performs astretching process (S202). In this case, the prediction image generationunit 102 allocates a value of the inside pixel to the outside pixel asin the case of the stretching process shown in FIG. 3B. The predictionimage generation unit 102 then generates a prediction image block(S203).

When the reference block does not include any boundary of the associatedslice (No in S201) and the reference block and the current block areincluded in the same slice (Yes in S204), the prediction imagegeneration unit 102 generates a prediction image block from thereference block without performing the stretching process (S207). It isto be noted that the same slice herein means a group of slices which areregarded as the same slice and include the current slice and theassociated slice.

When the reference block does not include any boundary of the associatedslice (No in S201) and the reference block and the current block are notincluded in the same slice (No in S204), the prediction image generationunit 102 performs the stretching process (S205). In this case, theprediction image generation unit 102 allocates a value of the insidepixel to the outside pixel as in the case of the stretching processshown in FIG. 4B. The prediction image generation unit 102 thengenerates a prediction image block (S206). It is to be noted that theprediction image generation unit 102 may previously determine on aper-sequence basis, on a per-picture basis, on a per-slice basis, or ona per-block basis, whether or not such a stretching process is to beperformed. When it has been previously determined that the stretchingprocess is not to be performed, the prediction image generation unit 102generates a prediction image block from the reference block withoutperforming the stretching process (S202, S205).

For example, when the images on the respective slices have similarcharacteristics, referring to another slice has no problem, which meansthat the need for the stretching process is low. In such a case, theprediction image generation unit 102 may determine that the stretchingprocess is not to be performed. By doing so, the processing efficiencyimproves.

Furthermore, such control on the stretching process may be applied onlyto the stretching process (S202) where the reference block includes aboundary as shown in FIG. 3B. Alternatively, the control on thestretching process may be applied only to the stretching process (S205)where the reference block is included in another slice as shown in FIG.4B.

It is to be noted that the prediction image generation unit 102 maydetermine based on identification information whether or not thestretching process is to be performed.

FIG. 6 is a flowchart showing a variation of the prediction imagegeneration process shown in FIG. 5. The prediction image generationprocess of FIG. 6 additionally includes, as compared to FIG. 5, aprocess (S211) of determining whether or not slice identificationinformation is the same.

In other words, when the reference block and the current block are notincluded in the same slice (No in S204), the prediction image generationunit 102 does not always have to perform the stretching process. Whenthe reference block and the current block are not included in the sameslice (No in S204), the prediction image generation unit 102 determinesbased on slice identification information whether or not the stretchingprocess is to be performed. Here, the slice identification informationis information which is allocated based on whether or not the imageshave continuity, how high the degree of similarity of the images is, andthe like factor. The slice identification information may be coded.

When the slice identification information is the same (Yes in S211), theprediction image generation unit 102 performs the stretching process(S205). On the other hand, the slice identification information is notthe same (No in S211), the prediction image generation unit 102generates a prediction image bock from the reference block withoutperforming the stretching process (S207).

For example, when the current slice and the associated slice have noimage continuity, the prediction image generation unit 102 generates aprediction image block from the reference block without performing thestretching process. For example, when the current slice and theassociated slice have a low level of similarity, the prediction imagegeneration unit 102 generates a prediction image block from thereference block without performing the stretching process. By doing so,when the effect of the stretching process is low, the stretching processis less likely to take place. Thus, the prediction image generationprocess is performed efficiently.

In FIG. 6, when the reference block and the current block are notincluded in the same slice (No in S204), the prediction image generationunit 102 determines whether or not the slice identification informationis the same. However, also when the reference block includes a boundaryof the associated slice (S201), the prediction image generation unit 102may determine whether or not the slice identification information is thesame. Subsequently, the prediction image generation unit 102 may performthe stretching process only when the slice identification information isthe same. By doing so, the prediction image generation process becomesmore efficient likewise.

Furthermore, on the basis of a result of the determination made in acoding process on whether or not the stretching process is to beperformed, the image decoding apparatus 100 may determine whether or notthe stretching process is to be performed. For example, the decodingunit 101 decodes applicability information which is informationdetermined and coded in the coding process and indicating whether or notthe value of the inside pixel is to be allocated to the outside pixel ofthe reference block. The prediction image generation unit 102 thenallocates the value of the inside pixel to the outside pixel of thereference block only when the applicability information indicates thatthe value of the inside pixel is to be allocated to the outside pixel.

Thus, the stretching process is controlled based on a result of thedetermination made in the coding process. The applicability informationmay be information for controlling the stretching process which isperformed on the reference block including a boundary of the associatedslice. Furthermore, the applicability information may be information forcontrolling the stretching process which is performed on the referenceblock which is entirely included in a non-associated slice differentfrom the associated slice.

FIG. 7A is a conceptual diagram showing the first example of a slicestructure according to this embodiment. In FIG. 7A, a first slice, asecond slice, and a third slice are included in a picture. For example,a typical aspect ratio of standard definition (SD) video is 4:3.Meanwhile, a typical aspect ratio of high definition (HD) video is 16:9.Accordingly, mapping SD video on HD video results in the picture shownin FIG. 7A based on a difference in aspect ratio.

The first slice at the middle in FIG. 7A is a region for displayingprimary video. The second slice on the left and the third slice on theright are regions in which, basically, no video is displayed, but whichare represented in a single color, black. However, subtitles oraccompanying information on the video may be displayed. Thus, theseregions are coded separately from the first slice for displaying theprimary video.

When the stretching process is not performed at a slice boundary,differences in image characteristics may decrease the image qualityespecially around the boundary between the first slice and the secondslice and around the boundary between the first slice and the thirdslice. Such a decrease in image quality is reduced by theabove-described stretching process. In particular, when pixels includedin the first slice and located around boundaries are stretched into thesecond slice on the left and the third slice on the right, the imagequality of the video which is displayed around the boundaries of thefirst slice improves.

FIG. 7B is a conceptual diagram showing the second example of the slicestructure according to this embodiment. FIG. 7B shows the example whereHD video is mapped on SD video. The first slice at the middle is aregion for displaying primary video. The second slice at the top and thethird slice at the bottom are regions in which, basically, no video isdisplayed, but which are represented in a single color, black. Also inthis case, the stretching process reduces a decrease in the imagequality around the boundary between the first slice and the second sliceand around the boundary between the first slice and the third slice.

FIG. 7C is a conceptual diagram showing the third example of the slicestructure according to this embodiment. As shown in FIG. 7C, a lackingnumber of pixels contained in video content may lead to the layout inwhich, as the first slice, the video content is located at the middleand, as the second slice, solid black video is located around the videocontent. Also in this case, the stretching process reduces a decrease inthe image quality around the boundary between the first slice and thesecond slice.

FIG. 8A is a conceptual diagram showing the third example of predictionimage generation according to this embodiment. In FIG. 8A, the currentblock is included in a first slice of the current picture. A motionvector of the current block points to the reference block located on theboundary between the first slice and a second slice in the referencepicture. In FIG. 8A, there is a gap between a slice boundary and asubstantive image boundary.

The substantive image boundary is, for example, a boundary between theregion which is represented in a single color, black, and the region inwhich primary video is displayed, as shown in FIG. 7A, etc. It is notnecessarily the case that the image including the plurality of regionsas shown in FIG. 7A, etc. is precisely divided into blocks each of whichis the minimum unit of processing. For example, a macroblock of 16 by 16pixels may be located across both the region which is represented in asingle color, black, and the region in which primary video is displayed.In addition, a slice, which depends on the region of a block, is locatedacross the two regions.

Thus, there may be a gap between a slice boundary and a substantiveimage boundary. The prediction image generation unit 102 may perform thestretching process according to such a gap.

FIG. 8B is a conceptual diagram showing an example of the stretchingprocess according to the prediction image generation shown in FIG. 8A.The prediction image generation unit 102 shifts the slice boundary basedon an offset value indicating a difference between the slice boundaryand the substantive image boundary.

The decoding unit 101 may obtain the offset value by decoding the offsetvalue determined in the coding process. Alternatively, the predictionimage generation unit 102 may determine the offset value in the same orthe like manner as the method of determining the offset value in thecoding process. For example, the prediction image generation unit 102may detect an edge portion of the reference picture as the substantiveimage boundary to determine the offset value.

Here, when the offset value is positive, the prediction image generationunit 102 shifts the first slice, which is the associated slice, in adirection such that the first slice is enlarged. When the offset valueis negative, the prediction image generation unit 102 shifts the firstslice, which is the associated slice, in a direction such that the firstslice is shrunk. It goes without saying that the relationship betweenthe plus and minus of the offset value and the shift direction may bereversed.

The prediction image generation unit 102 then allocates a value of aninside pixel to an outside pixel. The outside pixel here is a pixellocated outside the associated slice resulting from the shifting.

The inside pixel here is a pixel located inside the associated sliceresulting from the shifting. Thus, the prediction image generation unit102 generates a prediction image block by performing the stretchingprocess according to the gap.

FIG. 9A is a conceptual diagram showing the fourth example of predictionimage generation according to this embodiment. This shows an examplewhere a plurality of regions for displaying a plurality of video imagesis included in a single picture and the position and size of each of theregions change depending on the picture. For example, in the case of apersonal computer or the like, a plurality of display regions appear ona screen, and each of the display regions may change. FIG. 9A shows theexample in such a case.

The current picture and the reference picture in FIG. 9A each includethree slices A1, A2, and A3 which correspond to three respective displayregions. The slice Al of the current picture is the current slice andincludes the current block. A motion vector of the current block pointsto the reference block of the reference picture.

In such a case, the prediction image generation unit 102 stretches, intothe reference block, a pixel in the slice Al which is the associatedslice in the reference picture. However, the prediction image generationunit 102 needs to recognize the range of the slice A1 in the referencepicture. Otherwise, the prediction image generation unit 102 fails todetermine which pixel in the reference picture is to be stretched.Furthermore, unless whether or not the reference block is included inthe slice A1 is recognized, the prediction image generation unit 102fails to determine whether or not the stretching process is necessary.

The image decoding apparatus 100 may therefore include a storage unitwhich stores, into a memory unit, identification information foridentifying the range of the associated slice which is specified in eachof the pictures. With this, the prediction image generation unit 102 iscapable of determining an outside pixel and an inside pixel by referringto the identification information stored in the memory unit.

The identification information may include information on the sliceboundary. Furthermore, the identification information may includeidentification information for identifying a specific slice from among aplurality of slices included in a picture.

Furthermore, the image decoding apparatus 100 may obtain theidentification information from the coding apparatus. For example, thedecoding unit 101 decodes identification information coded on aper-picture basis in the coding process. The storage unit of the imagedecoding apparatus 100 stores the decoded identification informationinto the memory unit. Thus, by referring to the identificationinformation stored in the memory unit, the prediction image generationunit 102 is capable of specifying an associated slice which isassociated with the current slice.

The frequency of change of the slice range is assumed to be relativelylow. Thus, it may be that the storage unit of the image decodingapparatus 100 stores the identification information into the memory unitonly when the range of the associated slice has been changed.Furthermore, it may be that the decoding unit 101 decodes the codedidentification information only when the range of the associated slicehas been changed.

Furthermore, it may be that the decoding unit 101 first decodes anidentification signal indicating whether or not there is a change, anddecodes a more detailed signal only when there is a change. By doing so,the decoding unit 101 is capable of decoding a coded stream for which anincrease in code amount has been reduced.

Furthermore, as to whether or not slice identification information isincluded, it may be that the decoding unit 101 refers to informationindicated in upper-layer header information of the slice (i.e., theinformation indicating whether or not identification information isincluded) and performs a decoding process on the identificationinformation only when the identification information is included. Bydoing so, it is possible to reduce the process load of the decoding unit101.

FIG. 9B is a conceptual diagram showing an example of the identificationinformation according to the prediction image generation shown in FIG.9A. The identification information shown in FIG. 9B includes informationindicating which slice includes each pixel. Such identificationinformation is stored into the memory unit in association with eachpicture. With this, the range of the associated slice is identified.

It is to be noted that FIG. 9B is an example of a structure of theidentification information and the structure of the identificationinformation is not limited to the example of FIG. 9B. For example, theidentification information may include information for specifying aslice on a per-specific-range basis instead of per-pixel basis.

FIG. 10 is a structure diagram showing a specific example of the imagedecoding apparatus 100 shown in FIG. 1. The image decoding apparatus 100includes a control unit 104, a decoding unit 101, an inversequantization unit 105, an inverse frequency transform unit 106, anaddition unit 103, a deblocking filter unit 107, a storage unit 108, amemory unit 109, and a prediction image generation unit 102. Theprediction image generation unit 102 includes an intra-frame predictionunit 110, a motion compensation unit 111, and a switch unit 112.

The control unit 104 controls the whole image decoding apparatus 100.The decoding unit 101 decodes, from the coded stream, a motion vectorand a difference image block made up of frequency coefficient values.

The inverse quantization unit 105 inversely quantizes the differenceimage block. The inverse frequency transform unit 106 performs inversefrequency transform on the inversely-quantized difference image block.The addition unit 103 adds up the difference image block and aprediction image block, thereby reconstructing the current block.

The deblocking filter unit 107 removes block artifacts of the currentblock. The storage unit 108 stores the current block into the memoryunit 109. The memory unit 109 is a memory unit for holding a referencepicture.

The intra-frame prediction unit 110 generates a prediction image blockby intra-frame prediction. The motion compensation unit 111 generates aprediction image block by inter-frame prediction. The switch unit 112selectively switches between the intra-frame prediction and theinter-frame prediction under control of the control unit 104.

FIG. 11 is a flowchart showing a specific example of an image decodingprocess according to the image decoding apparatus 100 shown in FIG. 10.First, the decoding unit 101 decodes, from the coded stream, the motionvector and the difference image block for the current block (S301). Atthis time, the decoding unit 101 may decode identification informationfor identifying the range of each slice.

It may be that, only when the range of a slice has been changed, doesthe coded stream include the identification information for identifyingthe range of the slice. In this case, only when the range of the slicehas been changed, does the decoding unit 101 decode the identificationinformation for identifying the range of the slice. Furthermore, thedecoding unit 101 may decode applicability information indicatingwhether or not the value of the inside pixel that is a pixel locatedinside the associated block is to be allocated to the outside pixel thatis a pixel located outside the associated block.

Next, the inverse quantization unit 105 inversely quantizes thedifference image block obtained by the decoding unit 101 (S302). Next,the inverse frequency transform unit 106 performs inverse frequencytransform on the difference image block resulting from the inversequantization (S303). In other words, using the difference image blockmade up of frequency coefficient values, the inverse frequency transformunit 106 generates a difference image block made up of pixel values.

Next, the control unit 104 determines whether or not the current blockis an intra-frame prediction block that is decoded by intra-frameprediction (S304). When the current block is an intra-frame predictionblock (Yes in S304), the intra-frame prediction unit 110 generates aprediction image block by intra-frame prediction (S305).

On the other hand, when the current block is not the intra-frameprediction block (No in S304), that is, when the current block is aninter-frame prediction block, the motion compensation unit 111 generatesa prediction image block by inter-frame prediction (S306). At this time,the motion compensation unit 111 performs motion compensation byreferring to at least one reference picture stored in the memory unit109.

Furthermore, at this time, the motion compensation unit 111 generates aprediction image block by allocating the value of the inside pixel thatis a pixel located inside the associated block corresponding to thecurrent slice, to the outside pixel that is a pixel located outside theassociated block. Furthermore, the motion compensation unit 111 mayrefer to the identification information stored in the memory unit 109 toidentify the range of the associated slice and determine the outsidepixel and the inside pixel. Moreover, the motion compensation unit 111may change the control on the pixel stretching process based on theapplicability information.

Next, the addition unit 103 adds up the difference image block and theprediction image block (S307). By doing so, the addition unit 103reconstructs the current block. The deblocking filter unit 107 thenremoves block artifacts of the current block (S308).

Next, the storage unit 108 stores, into the memory unit 109, the currentblock processed by the deblocking filter unit 107 (S309). The storageunit 108 sequentially stores the current blocks, thereby storing aplurality of pictures as a plurality of reference pictures into thememory unit 109.

Here, the storage unit 108 may store, into the memory unit 109, theidentification information for identifying the range of the associatedslice which is specified in each of the reference pictures.

The identification information may be identification information decodedby the decoding unit 101. Furthermore, it may be that the storage unit108 stores the identification information into the memory unit 109 onlywhen the range of the associated slice has been changed.

Furthermore, it may be that an independent identification informationstorage unit separate from the storage unit 108 stores theidentification information into an independent identificationinformation memory unit separate from the memory unit 109. This meansthat the identification information may be handled separately from thereference picture. In addition, the identification information storageunit may be included in the control unit 104.

Through the above processing, the image decoding apparatus 100 generatesa prediction image by allocating the value of the inside pixel that is apixel located inside the associated slice, to the outside pixel that isa pixel located outside the associated slice. By doing so, even in thecase where an image is divided into a plurality of slices, a predictionimage is appropriately generated, resulting in reduction in the decreasein image quality.

An image coding apparatus according to this embodiment includes similarstructural elements which correspond to the structural elements of theimage decoding apparatus 100 according to this embodiment. The imagecoding apparatus according to this embodiment performs similarprocessing which corresponds to the processing performed by the imagedecoding apparatus 100 according to this embodiment. By doing so, theimage coding apparatus according to this embodiment is capable of codingan image including a plurality of slices while reducing both a decreasein image quality and a decrease in coding efficiency.

FIG. 12 is a structure diagram showing the image coding apparatusaccording to this embodiment. An image coding apparatus 400 shown inFIG. 12 codes, on a per-block basis, pictures each including slices. Theimage coding apparatus 400 includes a motion estimation unit 401, aprediction image generation unit 402, a subtraction unit 403, and acoding unit 404.

The motion estimation unit 401 estimates a motion vector (also referredto as a current motion vector). The motion vector here is a motionvector of a current block to be coded and is used to specify a referenceblock included in a reference picture.

The prediction image generation unit 402 specifies a reference block ina reference picture using the motion vector and generates a predictionimage block. At this time, the prediction image generation unit 402performs pixel stretching at a slice boundary as in the case of theprediction image generation unit 102 in the decoding process.Specifically, the prediction image generation unit 402 allocates a valueof an inside pixel that is a pixel located inside an associated slice toan outside pixel that is a pixel located outside the associated sliceand included in the reference block.

Here, the associated slice is a slice included in the reference pictureand has identity with a current slice to be coded which includes thecurrent block. The current slice and the associated slice have videocontent (content) in common. Typically, the spatial position of theassociated slice in the reference picture matches the spatial positionof the current slice in the current picture. Alternatively, the area ofthe associated slice and the area of the current slice spatiallyoverlap.

In other words, the associated slice is a slice which is included in thereference picture and corresponds to the current slice including thecurrent block.

The subtraction unit 403 subtracts the prediction image block from thecurrent block, thereby generating a difference image block.Specifically, the subtraction unit 403 subtracts the pixel valuesincluded in the prediction image block from the pixel values included inthe current block, thereby generating the difference image block.

The coding unit 404 codes the motion vector estimated by the motionestimation unit 401 and the difference image block generated by thesubtraction unit 403. Typically, the coding unit 404 performsvariable-length coding on the motion vector and the difference imageblock.

FIG. 13 is a flowchart showing an image coding process according to theimage coding apparatus 400 shown in FIG. 12.

First, the motion estimation unit 401 estimates the motion vector of thecurrent block (S401). Next, the prediction image generation unit 402allocates the value of the inside pixel to the outside pixel andgenerates the prediction image block (S402). Next, the subtraction unit403 subtracts the prediction image block from the current block, therebygenerating the difference image block (S403). Lastly, the coding unit404 codes the motion vector and the difference image block (S404). Bydoing so, the current block is coded.

FIG. 14 is a structure diagram showing a specific example of the imagecoding apparatus 400 shown in FIG. 12. The image coding apparatus 400shown in FIG. 14 includes a control unit 405, the motion estimation unit401, the subtraction unit 403, a frequency transform unit 406, aquantization unit 407, the coding unit 404, an inverse quantization unit408, an inverse frequency transform unit 409, an addition unit 410, adeblocking filter unit 411, a storage unit 412, a memory unit 413, andthe prediction image generation unit 402. The prediction imagegeneration unit 402 includes an intra-frame prediction unit 414, amotion compensation unit 415, and a switch unit 416.

The control unit 405 controls the whole image coding apparatus 400. Themotion estimation unit 401 estimates the motion vector of the currentblock included in an input image. The subtraction unit 403 subtracts theprediction image block from the current block, thereby generating thedifference image block.

The frequency transform unit 406 transforms the difference image blockmade up of pixel values into the difference image block made up offrequency coefficient values. The quantization unit 407 quantizes thedifference image block made up of frequency coefficient values. Thecoding unit 404 codes the motion vector and the quantized differenceimage block.

The inverse quantization unit 408 inversely quantizes the quantizeddifference image block. The inverse frequency transform unit 409performs inverse frequency transform on the inversely-quantizeddifference image block, thereby generating a difference image block madeup of pixel values. The addition unit 410 adds up the difference imageblock and the prediction image block, thereby generating a reconstructedimage block approximate to the original version of the current block.

The deblocking filter unit 411 removes block artifacts of thereconstructed image block. The storage unit 412 stores the reconstructedimage block into the memory unit 413. The memory unit 413 is a memoryunit for holding a reference picture.

The intra-frame prediction unit 414 generates a prediction image blockby intra-frame prediction. The motion compensation unit 415 generates aprediction image block by inter-frame prediction. The switch unit 416selectively switches between the intra-frame prediction and theinter-frame prediction under control of the control unit 405.

FIG. 15 is a flowchart showing a specific example of an image codingprocess according to the image coding apparatus 400 shown in FIG. 14.First, the control unit 405 determines whether or not the current blockin an input image is an intra-frame prediction block that is coded byintra-frame prediction (S501). When the current block is an intra-frameprediction block (Yes in S501), the intra-frame prediction unit 414generates a prediction image block by intra-frame prediction (S502).

On the other hand, when the current block is not the intra-frameprediction block (No in S501), that is, when the current block is aninter-frame prediction block, the motion estimation unit 401 estimatesthe motion vector of the current block (S503). The motion compensationunit 415 then generates a prediction image block by inter-frameprediction (S504). At this time, the motion compensation unit 415performs motion compensation by referring to at least one referencepicture stored in the memory unit 413.

Furthermore, at this time, the motion compensation unit 415 generates aprediction image block by allocating the value of the inside pixel thatis a pixel located inside the associated block corresponding to thecurrent slice, to the outside pixel that is a pixel located outside theassociated block. Furthermore, the motion compensation unit 415 mayrefer to the identification information stored in the memory unit 413 toidentify the range of the associated slice and determine the outsidepixel and the inside pixel.

Moreover, the motion compensation unit 415 may change the control on thepixel stretching process based on applicability information indicatingwhether or not the value of the inside pixel is to be allocated to theoutside pixel. In this case, the control unit 405 may determine whetheror not the value of the inside pixel is to be allocated to the outsidepixel, and generate the applicability information to be used by themotion compensation unit 415.

Next, the subtraction unit 403 subtracts the prediction image block fromthe current block, thereby generating the difference image block (S505).The frequency transform unit 406 then transforms the difference imageblock made up of pixel values into the difference image block made up offrequency coefficient values (S506). Subsequently, the quantization unit407 quantizes the difference image block made up of frequencycoefficient values (S507).

Next, the coding unit 404 codes the quantized difference image block,thereby generating a coded stream (S508). At this time, when the currentblock is an inter-prediction block, the coding unit 404 codes the motionvector. Furthermore, the coding unit 404 may code identificationinformation for identifying the range of each slice. Moreover, it may bethat, only when the range of a slice has been changed, does the codingunit 404 code identification information for identifying the range ofthe slice.

Here, as is explained on the operation in the decoding process, it maybe that, as the identification information, the slice identificationinformation is allocated based on whether or not the images havecontinuity, how high the degree of similarity of the images is, and thelike factor. Accordingly, the stretching process is not performed onslices having the same characteristics, but is performed only on sliceshaving different characteristics or on a boundary of such slices. Thus,the coding efficiency improves.

Furthermore, the coding unit 404 may code applicability informationindicating whether or not the value of the inside pixel is to beallocated to the outside pixel.

Next, the inverse quantization unit 408 inversely quantizes thequantized difference image block (S509). The inverse frequency transformunit 409 performs inverse frequency transform on the inversely-quantizeddifference image block. In other words, using the difference image blockmade up of frequency coefficient values, the inverse frequency transformunit 409 generates a difference image block made up of pixel values(S510).

Next, the addition unit 410 adds up the difference image block and theprediction image block (S511). By doing so, the addition unit 410generates a reconstructed image block. The deblocking filter unit 411removes block artifacts from the reconstructed image block (S512).

Next, the storage unit 412 stores, into the memory unit 413, thereconstructed image block processed by the deblocking filter unit 411(S513). The storage unit 412 sequentially stores the reconstructed imageblocks, thereby storing a plurality of pictures as a plurality ofreference pictures into the memory unit 413.

Here, the storage unit 412 may store, into the memory unit 413, theidentification information for identifying the range of the associatedslice which is specified in each of the reference pictures. Furthermore,it may be that, only when the range of the associated slice has beenchanged, the storage unit 412 stores the identification information intothe memory unit 413.

Furthermore, it may be that an independent identification informationstorage unit separate from the storage unit 412 stores theidentification information into an independent identificationinformation memory unit separate from the memory unit 413. This meansthat the identification information may be handled separately from thereference picture. In addition, the identification information storageunit may be included in the control unit 405.

Through the above processing, the image coding apparatus 400 is capableof appropriately generating a prediction image even in the case where animage is divided into a plurality of slices. It is to be noted that theabove explanation describes representative processing of the imagecoding apparatus 400. The image coding apparatus 400 is capable ofperforming not only the above-described processing, but also processingsimilar to the processing performed by the image decoding apparatus 100.For example, the image coding apparatus 400 is capable of performing theprocessing shown in FIGS. 3A to 9B.

As above, the image decoding apparatus 100 and the image codingapparatus 400 according to this embodiment each generate a predictionimage by allocating the value of the inside pixel that is a pixellocated inside the associated slice, to the outside pixel that is apixel located outside the associated slice. By doing so, the predictionaccuracy improves. Thus, even in the case where an image is divided intoa plurality of slices, a prediction image is appropriately generated,resulting in reduction in the decrease in image quality and in thedecrease in coding efficiency.

Although the prediction image is generated from a single referencepicture in the above description, the prediction image may be generatedfrom a plurality of reference pictures. Also in this case, the imagedecoding apparatus 100 and the image coding apparatus 400 are eachcapable of generating a prediction image block by allocating the valueof the inside pixel to the outside pixel in the same or like manner.

Furthermore, the coding unit 404 of the image coding apparatus 400 maycode the motion vector by coding the motion vector difference obtainedby subtracting the prediction motion vector from the motion vector. Inthis case, the decoding unit 101 of the image decoding apparatus 100decodes the motion vector by decoding the motion vector difference andadding up the decoded motion vector difference and the prediction motionvector. Here, the prediction motion vector is a motion vector predictedbased on a motion vector of a block adjacent to the current block.

Although the above describes the image decoding apparatus and the imagecoding apparatus according to an implementation of the present inventionhave been described base on the embodiment, the present invention is notlimited to the embodiment. The present invention includes an embodimentwith some modifications on the embodiment that are conceived by a personskilled in the art, and another embodiment obtained through anycombinations of the structural elements in the embodiment.

For example, the process performed by a specific processing unit may beperformed by another processing unit. Furthermore, the sequence ofperforming the processes may be changed, and a plurality of processesmay be performed in parallel.

Furthermore, the image decoding apparatus and the image coding apparatusaccording to an implementation of the present invention may be providedas an image coding and decoding apparatus which includes any combinationof the structural elements of the image decoding apparatus and the imagecoding apparatus. For example, the image coding and decoding apparatusaccording to an implementation of the present invention may include, asan image decoding unit, the image decoding apparatus according to animplementation of the present invention and further include, as an imagecoding unit, the image coding apparatus according to the implementationof the present invention.

Furthermore, the present invention can be implemented not only as theimage decoding apparatus and the image coding apparatus, but also as amethod which includes, as steps, the processing means included in theimage decoding apparatus and the image coding apparatus. For example,these steps are performed by a computer. In addition, the presentinvention can be implemented as a program which causes a computer toperform the steps included in the method. Furthermore, the presentinvention can be implemented as a non-transitory computer-readablerecording medium such as a compact disc read-only memory (CD-ROM) onwhich the program has been recorded.

Furthermore, the structural elements included in the image decodingapparatus and the image coding apparatus may be implemented in the formof large scale integration (LSI) that is an integrated circuit. Thesestructural elements may be each provided on a single chip, and part orall of them may be formed into a single chip. For example, thestructural elements other than the memory unit may be formed into asingle chip. The name used here is LSI, but it may also be called anintegral circuit (IC), system LSI, super LSI, or ultra LSI depending onthe degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The structural elements included in theimage decoding apparatus and the image coding apparatus can beintegrated using such a technology.

Embodiment 2

The processing described in the above embodiment can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configuration of themoving picture coding method (the image coding method) or the movingpicture decoding method (the image decoding method) described in theabove embodiment. The recording media may be any recording media as longas the program can be recorded, such as a magnetic disk, an opticaldisk, a magnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (theimage coding method) and the moving picture decoding method (the imagedecoding method) described in the above embodiment and systems usingthem will be described. This system is characterized by including animage coding and decoding apparatus composed of the image codingapparatus using the image coding method and the image decoding apparatususing the image decoding method. The other structure of the system canbe appropriately changed depending on situations.

FIG. 16 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex 106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 16, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital video camera, iscapable of capturing both still images and video. Furthermore, thecellular phone ex114 may be the one that meets any of the standards suchas Global System for Mobile Communications (GSM) (registered trademark),Code Division Multiple Access (CDMA), Wideband-Code Division MultipleAccess (W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described in the above embodiment (that is, the systemfunctions as the image coding apparatus according to an implementationof the present invention), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the received data (that is, the system functionsas the image decoding apparatus according to the implementation of thepresent invention).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be synthesized intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.

Furthermore, when the cellular phone ex114 is equipped with a camera,the image data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (the image coding apparatus)and the moving picture decoding apparatus (the image decoding apparatus)described in the above embodiment may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 17. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in the above embodiment (thatis, the video data is data coded by the image coding apparatus accordingto an implementation of the present invention). Upon receipt of themultiplexed data, the broadcast satellite ex202 transmits radio wavesfor broadcasting. Then, a home-use antenna ex204 with a satellitebroadcast reception function receives the radio waves. Next, a devicesuch as a television (receiver) ex300 and a set top box (STB) ex217decodes the received multiplexed data, and reproduces the decoded data(that is, the system functions as the image decoding apparatus accordingto an implementation of the present invention).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording media ex215, such as a DVD anda BD, or (ii) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown inthe above embodiment. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 18 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin the above embodiment. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

Furthermore, the television ex300 further includes: a signal processingunit ex306 including an audio signal processing unit ex304 and a videosignal processing unit ex305 (functioning as the image coding apparatusor the image decoding apparatus according to an implementation of thepresent invention) that decode audio data and video data and code audiodata and video data, respectively; and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation.

Furthermore, the television ex300 includes a control unit ex310 thatcontrols overall each constituent element of the television ex300, and apower supply circuit unit ex311 that supplies power to each of theelements. Other than the operation input unit ex312, the interface unitex317 may include: a bridge ex313 that is connected to an externaldevice, such as the reader/recorder ex218; a slot unit ex314 forenabling attachment of the recording medium ex216, such as an SD card; adriver ex315 to be connected to an external recording medium, such as ahard disk; and a modem ex316 to be connected to a telephone network.Here, the recording medium ex216 can electrically record informationusing a non-volatile/volatile semiconductor memory element for storage.The constituent elements of the television ex300 are connected to eachother through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in the above embodiment, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in the above embodiment. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, although notillustrated, data may be stored in a buffer so that the system overflowand underflow may be avoided between the modulation/demodulation unitex302 and the multiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 19 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215.

The disk motor ex405 rotates the recording medium ex215. The servocontrol unit ex406 moves the optical head ex401 to a predeterminedinformation track while controlling the rotation drive of the disk motorex405 so as to follow the laser spot. The system control unit ex407controls overall the information reproducing/recording unit ex400. Thereading and writing processes can be implemented by the system controlunit ex407 using various information stored in the buffer ex404 andgenerating and adding new information as necessary, and by themodulation recording unit ex402, the reproduction demodulating unitex403, and the servo control unit ex406 that record and reproduceinformation through the optical head ex401 while being operated in acoordinated manner. The system control unit ex407 includes, for example,a microprocessor, and executes processing by causing a computer toexecute a program for read and write.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 20 schematically illustrates the recording medium ex215 that is theoptical disk. On the recording surface of the recording medium ex215,guide grooves are spirally formed, and an information track ex230records, in advance, address information indicating an absolute positionon the disk according to change in a shape of the guide grooves. Theaddress information includes information for determining positions ofrecording blocks ex231 that are a unit for recording data. Reproducingthe information track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 18. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 21A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin the above embodiment. The cellular phone ex114 includes: an antennaex350 for transmitting and receiving radio waves through the basestation ex110; a camera unit ex365 capable of capturing moving and stillimages; and a display unit ex358 such as a liquid crystal display fordisplaying the data such as decoded video captured by the camera unitex365 or received by the antenna ex350. The cellular phone ex114 furtherincludes: a main body unit including an operation key unit ex366; anaudio output unit ex357 such as a speaker for output of audio; an audioinput unit ex356 such as a microphone for input of audio; a memory unitex367 for storing captured video or still pictures, recorded audio,coded or decoded data of the received video, the still pictures,e-mails, or others; and a slot unit ex364 that is an interface unit fora recording medium that stores data in the same manner as the memoryunit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 21B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a bus ex370, to a power supplycircuit unit ex361, an operation input control unit ex362, a videosignal processing unit ex355, a camera interface unit ex363, a liquidcrystal display (LCD) control unit ex359, a modulation/demodulation unitex352, a multiplexing/demultiplexing unit ex353, an audio signalprocessing unit ex354, the slot unit ex364, and the memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in the above embodiment (that is, thevideo signal processing unit ex355 functions as the image codingapparatus according to an implementation of the present invention), andtransmits the coded video data to the multiplexing/demultiplexing unitex353. In contrast, during when the camera unit ex365 captures video,still images, and others, the audio signal processing unit ex354 codesaudio signals collected by the audio input unit ex356, and transmits thecoded audio data to the multiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit (themodulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in the above embodiment (that is, the video signalprocessing unit ex355 functions as the image decoding apparatusaccording to an implementation of the present invention), and then thedisplay unit ex358 displays, for instance, the video and still imagesincluded in the video file linked to the Web page via the LCD controlunit ex359. Furthermore, the audio signal processing unit ex354 decodesthe audio signal, and the audio output unit ex357 provides the audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably has 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in the above embodiment can be used in any of thedevices and systems described. Thus, the advantages described in theabove embodiment can be obtained.

Furthermore, the present invention is not limited to the aboveembodiment, and various modifications and revisions are possible withoutdeparting from the scope of the present invention.

Embodiment 3

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in the above embodiment and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG4-AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconforms cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in the above embodiment will behereinafter described. The multiplexed data is a digital stream in theMPEG2-Transport Stream format.

FIG. 22 illustrates a structure of the multiplexed data. As illustratedin FIG. 22, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in the above embodiment, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary video to be mixed with the primary audio.

FIG. 23 schematically illustrates how data is multiplexed.

First, a video stream ex235 composed of video frames and an audio streamex238 composed of audio frames are transformed into a stream of PESpackets ex236 and a stream of PES packets ex239, and further into TSpackets ex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 24 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 24 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 24, the video stream is divided into pictures as I-pictures,B-pictures, and P-pictures each of which is a video presentation unit,and the pictures are stored in a payload of each of the PES packets.Each of the PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 25 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 25. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information onthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 26 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationon the multiplexed data as shown in FIG. 27. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 27, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 28, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In this embodiment, the multiplexed data to be used is of a stream typeincluded in the PMT. Furthermore, when the multiplexed data is recordedon a recording medium, the video stream attribute information includedin the multiplexed data information is used. More specifically, themoving picture coding method or the moving picture coding apparatusdescribed in the above embodiment includes a step or a unit forallocating unique information indicating video data generated by themoving picture coding method or the moving picture coding apparatus inthe above embodiment, to the stream type included in the PMT or thevideo stream attribute information. With the configuration, the videodata generated by the moving picture coding method or the moving picturecoding apparatus described in the above embodiment can be distinguishedfrom video data that conforms to another standard.

Furthermore, FIG. 29 illustrates steps of the moving picture decodingmethod according to this embodiment. In Step exS100, the stream typeincluded in the PMT or the video stream attribute information isobtained from the multiplexed data. Next, in Step exS101, it isdetermined whether or not the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus inthe above embodiment. When it is determined that the stream type or thevideo stream attribute information indicates that the multiplexed datais generated by the moving picture coding method or the moving picturecoding apparatus in the above embodiment, in Step exS102, decoding isperformed by the moving picture decoding method in the above embodiment.Furthermore, when the stream type or the video stream attributeinformation indicates conformance to the conventional standards, such asMPEG-2, MPEG4-AVC, and VC-1, in Step exS103, decoding is performed by amoving picture decoding method in conformity with the conventionalstandards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in the above embodiment can perform decoding. Evenwhen multiplexed data that conforms to a different standard, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in this embodiment can be used in thedevices and systems described above.

Embodiment 4

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in the above embodiment is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example, FIG. 30 illustrates a configuration of an LSI ex500 thatis made into one chip. The LSI ex500 includes elements ex501, ex502,ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to be describedbelow, and the elements are connected to each other through a bus ex510.The power supply circuit unit ex505 is activated by supplying each ofthe elements with power when the power supply circuit unit ex505 isturned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in the above embodiment.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recording mediaex215. When data sets are multiplexed, the data should be temporarilystored in the buffer ex508 so that the data sets are synchronized witheach other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, and the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present inventionis applied to biotechnology.

Embodiment 5

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in the above embodiment isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG4-AVC, and VC-1 is decoded, the processingamount probably increases. Thus, the LSI ex500 needs to be set to adriving frequency higher than that of the CPU ex502 to be used whenvideo data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 31illustrates a configuration ex800 in this embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in theabove embodiment. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in the above embodiment to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in the above embodiment. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 30.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in the above embodiment and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 30. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment 3 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 3 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 33. The driving frequency can be selected by storing the look-uptable in the buffer ex508 or in an internal memory of an LSI, andreferring to the look-up table by the CPU ex502.

FIG. 32 illustrates steps for executing a method in this embodiment.First, in Step exS200, the signal processing unit ex507 obtainsidentification information from the multiplexed data. Next, in StepexS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described in theabove embodiment, based on the identification information. When thevideo data is generated by the coding method and the coding apparatusdescribed in the above embodiment, in Step exS202, the CPU ex502transmits a signal for setting the driving frequency to a higher drivingfrequency to the driving frequency control unit ex512. Then, the drivingfrequency control unit ex512 sets the driving frequency to the higherdriving frequency. On the other hand, when the identificationinformation indicates that the video data conforms to the conventionalstandard, such as MPEG-2, MPEG4-AVC, and VC-1, in Step exS203, the CPUex502 transmits a signal for setting the driving frequency to a lowerdriving frequency to the driving frequency control unit ex512. Then, thedriving frequency control unit ex512 sets the driving frequency to thelower driving frequency than that in the case where the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in the above embodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG4-AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in the above embodiment, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower.

For example, when the identification information indicates that thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in the above embodiment, thevoltage to be applied to the LSI ex500 or the apparatus including theLSI ex500 is probably set higher. When the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG4-AVC, and VC-1, the voltage to be applied to theLSI ex500 or the apparatus including the LSI ex500 is probably setlower. As another example, when the identification information indicatesthat the video data is generated by the moving picture coding method andthe moving picture coding apparatus described in the above embodiment,the driving of the CPU ex502 does not probably have to be suspended.When the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1, the driving of the CPU ex502 is probably suspended at a given timebecause the CPU ex502 has extra processing capacity. Even when theidentification information indicates that the video data is generated bythe moving picture coding method and the moving picture coding apparatusdescribed in the above embodiment, in the case where the CPU ex502 hasextra processing capacity, the driving of the CPU ex502 is probablysuspended at a given time. In such a case, the suspending time isprobably set shorter than that in the case where when the identificationinformation indicates that the video data conforms to the conventionalstandard, such as MPEG-2, MPEG4-AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the

LSI ex500 or the apparatus including the LSI ex500 is driven using abattery, the battery life can be extended with the power conservationeffect.

Embodiment 6

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a mobile phone. In order to enable decoding the pluralityof video data that conforms to the different standards, the signalprocessing unit ex507 of the LSI ex500 needs to conform to the differentstandards. However, the problems of increase in the scale of the circuitof the LSI ex500 and increase in the cost arise with the individual useof the signal processing units ex507 that conform to the respectivestandards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in the above embodiment and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG4-AVC, and VC-1 are partly shared. Ex900 in FIG. 34A showsan example of the configuration. For example, the moving picturedecoding method described in the above embodiment and the moving picturedecoding method that conforms to MPEG4-AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensation. The details of processingto be shared probably include use of a decoding processing unit ex902that conforms to MPEG4-AVC. In contrast, a dedicated decoding processingunit ex901 is probably used for other processing that does not conformto MPEG4-AVC and is unique to the present invention. Since the presentinvention is characterized by inter prediction in particular, forexample, the dedicated decoding processing unit ex901 is used for interprediction. Otherwise, the decoding processing unit is probably sharedfor one of the entropy coding, deblocking filtering, orthogonaltransform, and quantization, or all of the processing. The decodingprocessing unit for implementing the moving picture decoding methoddescribed in the above embodiment may be shared for the processing to beshared, and a dedicated decoding processing unit may be used forprocessing unique to that of MPEG4-AVC.

Furthermore, ex1000 in FIG. 34B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to the present invention, a dedicated decoding processing unitex1002 that supports the processing unique to another conventionalstandard, and a decoding processing unit ex1003 that supports processingto be shared between the moving picture decoding method in the presentinvention and the conventional moving picture decoding method. Here, thededicated decoding processing units ex1001 and ex1002 are notnecessarily specialized for the processing of the present invention andthe processing of the conventional standard, respectively, and may bethe ones capable of implementing general processing. Furthermore, theconfiguration of this embodiment can be implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding method inthe present invention and the moving picture decoding method inconformity with the conventional standard.

INDUSTRIAL APPLICABILITY

The image decoding method and the image coding method according toimplementations of the present invention can be used in televisions,digital video recorders, car navigation systems, cellular phones,digital cameras, or digital video cameras, for example.

REFERENCE SIGNS LIST

100 Image decoding apparatus

101 Decoding unit

102, 402 Prediction image generation unit

103, 410 Addition unit

104, 405 Control unit

105, 408 Inverse quantization unit

106, 409 Inverse frequency transform unit

107, 411 Deblocking filter unit

108, 412 Storage unit

109, 413 Memory unit

110, 414 Intra-frame prediction unit

111, 415 Motion compensation unit

112, 416 Switch unit

400 Image coding apparatus

401 Motion estimation unit

403 Subtraction unit

404 Coding unit

406 Frequency transform unit

407 Quantization unit

1. An image decoding method for decoding, on a per-block basis, pictureseach including slices, the method comprising: decoding a current motionvector and a difference image block, the current motion vector being amotion vector of a current block to be decoded and specifying areference block included in a reference picture, and the differenceimage block indicating a difference between the current block and aprediction image block; generating the prediction image block byallocating a value of an inside pixel to an outside pixel, the insidepixel being a pixel located inside an associated slice, the outsidepixel being a pixel located outside the associated slice and included inthe reference block specified by the current motion vector, and theassociated slice being a slice included in the reference picture andcorresponding to a current slice to be decoded which includes thecurrent block; and adding up the difference image block and theprediction image block to reconstruct the current block.
 2. The imagedecoding method according to claim 1, comprising storing, into a memoryunit, identification information for identifying a range of theassociated slice specified in each of reference pictures, wherein in thegenerating, the outside pixel and the inside pixel are determined byreferring to the identification information stored in the memory unit,and the value of the inside pixel is allocated to the outside pixel togenerate the prediction image block.
 3. The image decoding methodaccording to claim 2, wherein in the decoding, the identificationinformation is decoded, and in the storing, the identificationinformation resulting from the decoding is stored into the memory unit.4. The image decoding method according to claim 2, wherein in thestoring, the identification information is stored into the memory unitwhen the range of the associated slice has been changed.
 5. The imagedecoding method according claim 1, wherein in the decoding,applicability information is decoded, the applicability informationindicating whether or not the value of the inside pixel is to beallocated to the outside pixel of the reference block, and in thegenerating, when the applicability information indicates that the valueof the inside pixel is to be allocated to the outside pixel, the valueof the inside pixel is allocated to the outside pixel of the referenceblock to generate the prediction image block.
 6. The image decodingmethod according to claim 5, wherein the decoding includes decoding theapplicability information indicating whether or not the value of theinside pixel is to be allocated to the outside pixel of the referenceblock which includes a boundary of the associated slice, and in thegenerating, when the applicability information indicates that the valueof the inside pixel is to be allocated, the value of the inside pixel isallocated to the outside pixel of the reference block which includes theboundary of the associated slice, to generate the prediction imageblock.
 7. The image decoding method according to claim 5, wherein thedecoding includes decoding the applicability information indicatingwhether or not the value of the inside pixel is to be allocated to theoutside pixel of the reference block which is entirely included in anon-associated slice different from the associated slice, and in thegenerating, when the applicability information indicates that the valueof the inside pixel is to be allocated, the value of the inside pixel isallocated to the outside pixel of the reference block which is entirelyincluded in the non-associated slice, to generate the prediction imageblock.
 8. The image decoding method according to claim 1, wherein in thedecoding, an offset value for shifting the associated slice is decoded,and in the generating, the associated slice is shifted by as much as theoffset value, and the value of the inside pixel which is a pixel locatedinside the associated slice resulting from the shifting is allocated tothe outside pixel which is a pixel located outside the associated sliceresulting from the shifting, to generate the prediction image block. 9.The image decoding method according to claim 1, wherein in thegenerating, the value of the inside pixel which is a pixel spatiallyclosest to the outside pixel among pixels included in the associatedslice is allocated to the outside pixel, to generate the predictionimage block.
 10. An image coding method for coding, on a per-blockbasis, pictures each including slices, the method comprising: estimatinga current motion vector which is a motion vector of a current block tobe coded and specifies a reference block included in a referencepicture; generating a prediction image block by allocating a value of aninside pixel to an outside pixel, the inside pixel being a pixel locatedinside an associated slice, the outside pixel being a pixel locatedoutside the associated slice and included in the reference blockspecified by the current motion vector, and the associated slice being aslice included in the reference picture and corresponding to a currentslice to be coded which includes the current block; subtracting theprediction image block from the current block to generate a differenceimage block; and coding the current motion vector and the differenceimage block.
 11. The image coding method according to claim 10,comprising storing, into a memory unit, identification information foridentifying a range of the associated slice specified in each ofreference pictures, wherein in the generating, the outside pixel and theinside pixel are determined by referring to the identificationinformation stored in the memory unit, and the value of the inside pixelis allocated to the outside pixel to generate the prediction imageblock.
 12. The image coding method according to claim 11, wherein in thecoding, the identification information is coded.
 13. The image codingmethod according to claim 11, wherein in the storing, the identificationinformation is stored into the memory unit when the range of theassociated slice has been changed.
 14. The image coding method accordingto claim 10, wherein in the coding, applicability information is coded,the applicability information indicating whether or not the value of theinside pixel is to be allocated to the outside pixel of the referenceblock, and in the generating, when the applicability informationindicates that the value of the inside pixel is to be allocated to theoutside pixel, the value of the inside pixel is allocated to the outsidepixel of the reference block to generate the prediction image block. 15.The image coding method according to claim 14, wherein the codingincludes coding the applicability information indicating whether or notthe value of the inside pixel is to be allocated to the outside pixel ofthe reference block which includes a boundary of the associated slice,and in the generating, when the applicability information indicates thatthe value of the inside pixel is to be allocated, the value of theinside pixel is allocated to the outside pixel of the reference blockwhich includes the boundary of the associated slice, to generate theprediction image block.
 16. The image coding method according to claim14, wherein the coding includes coding the applicability informationindicating whether or not the value of the inside pixel is to beallocated to the outside pixel of the reference block which is entirelyincluded in a non-associated slice different from the associated slice,and in the generating, when the applicability information indicates thatthe value of the inside pixel is to be allocated, the value of theinside pixel is allocated to the outside pixel of the reference blockwhich is entirely included in the non-associated slice, to generate theprediction image block.
 17. The image coding method according to claim10, wherein in the coding, an offset value for shifting the associatedslice is coded, and in the generating, the associated slice is shiftedby as much as the offset value, and the value of the inside pixel whichis a pixel located inside the associated slice resulting from theshifting is allocated to the outside pixel which is a pixel locatedoutside the associated slice resulting from the shifting, to generatethe prediction image block.
 18. The image coding method according toclaim 10, wherein in the generating, the value of the inside pixel whichis a pixel spatially closest to the outside pixel among pixels includedin the associated slice is allocated to the outside pixel, to generatethe prediction image block.
 19. An image decoding apparatus whichperforms the image decoding method according to claim
 1. 20. An imagecoding apparatus which performs the image coding method according toclaim 10.